A design method of edge improvement

Abstract

The present application relates to the field of contact lens technology, and particularly relates to a design method of an improved edge. The method comprises the following steps: defining lens parameters: determining the optical zone convex curvature radius R 凸1 and calculating the sag S 凸1 ag; designing the middle arc segment R 凸2 ; introducing the transition arc segment R 凸3 . The present application introduces the middle arc segment R 凸2 and the transition arc segment R 凸3 , optimizes the connection mode of the arc segments, reduces the lens middle peripheral thickness, improves the comfort, wherein the middle peripheral thickness ET is accurately controlled within 0.3mm-0.6mm, the wearing pressure distribution is more uniform, the smooth transition arc segment R 凸3 reduces the edge lifting height, the tear exchange rate is improved, the risk of corneal hypoxia is reduced, the sharp corner depression is eliminated, the stress concentration area is reduced, the lens breakage rate is reduced, the transition arc segment width BFW2 is designed to avoid narrow deep ring bands, and the cleaning efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of contact lens, in particular, to a design method of edge improvement type. BACKGROUND

[0002] Scleral and toric lenses have some advantages over corneal lenses. Irregularities in the corneal surface caused by keratoconus and pachymorphic degeneration of the corneal limbus are covered by the scleral lens, which can restore clear vision by reconstructing a smooth anterior surface. Some patients have damaged corneal tissue, and the scleral lens can form a liquid storage pool behind the lens, which can protect the cornea and even help the cornea heal. In addition, corneal lenses are prone to displacement, and scleral and toric lenses are not prone to displacement because they can span the position of the upper and lower eyelids.

[0003] In addition, it is generally believed that large-diameter scleral lenses are more comfortable than corneal lenses. Part of the reason is that the scleral lens is not prone to sliding in the eye, and the non-sliding lens means that the exchange of tear fluid is relatively easy. If the tear fluid is not exchanged for a long time when wearing a scleral lens, some complications may occur. In order to solve the problem of tear fluid exchange, the last edge arc of the inner surface of the scleral lens is raised more in the design. The raising of the edge arc changes the problem of tear fluid exchange, but because the convex surface of the existing scleral lens mainly adopts a two-arc design, the central thickness of the edge-raised lens also increases, accompanied by a decrease in comfort. SUMMARY

[0004] The purpose of the present application is to provide a design method of edge improvement type to solve the problem of reduced comfort after flattening the edge arc in the background art.

[0005] To achieve the above purpose, the present application provides a design method of edge improvement type, comprising the following steps:

[0006] S1, defining lens parameters: determining the optical zone convex curvature radius R according to the lens power 凸1 , and calculating the sag Sag 凸1 ;

[0007] S2, designing the middle arc segment R 凸2 : solving the middle arc segment curvature radius R 凸2 to control the central thickness ET;

[0008] S3, introducing the transition arc segment R 凸3 : solving the transition arc segment curvature radius R 凸3 to smoothly connect the middle arc segment and the edge arc segment;

[0009] S4, Optimization of edge connection: Ensure that the transition arc segment width meets the requirements to eliminate lens edge depression and stress concentration.

[0010] Compared with the prior art, the beneficial effects of the present application are:

[0011] 1. Significant improvement in comfort: The ET of the middle peripheral part is accurately controlled at 0.3-0.6 mm, which is reduced by 30% compared with the traditional design (ET≥0.7 mm), and the pressure distribution is more uniform when worn.

[0012] 2. Optimization of tear exchange efficiency: The smooth transition arc segment (R 凸3 ) reduces the edge lifting height, and the tear exchange rate is increased by 20%, reducing the risk of corneal hypoxia.

[0013] 3. Enhanced durability: Eliminate sharp corner depression, reduce stress concentration area by 50%, and reduce lens breakage rate by 40%.

[0014] 4. Improved easy cleaning: The transition arc segment width BFW2 design avoids narrow deep ring belt, and the cleaning efficiency is improved by 35%.

[0015] 5. Simplified manufacturing process: Three-section turning (optical zone, intermediate arc segment, edge arc segment) of numerical control lathe reduces processing steps, and the yield rate is increased to 95%. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The middle peripheral thickness design diagram of the present application.

[0017] Figure 2 The existing middle peripheral thickness design diagram.

[0018] Figure 3 The comparison diagram of the middle peripheral thickness of the present application and the existing one.

[0019] Figure 4 The numerical control lathe turning processing schematic diagram of the lens of the present application. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] In a specific embodiment, as Figure 1 shown, the present application provides a design method for improved edge, including the following steps:

[0022] First step, define lens parameters: according to the lens power to determine the optical zone convex curvature radius R 凸1 , and calculate its sag Sag 凸1 .

[0023] CT is the center thickness of the lens, the range is 0.08mm-0.60mm, according to the requirements of lens power, the value range of CT can be further divided, ET is the parameter to meet the control of lens edge thinning, the designer combines the lens durability, in addition, the material of the lens also needs to be fully considered, the power of the lens, the application gives the selection suggestion:

[0024] Table 1 is the related reference parameters when selecting lens power

[0025] Serial number Material of lens Power of lens Central thickness range of lens Suggested ET thickness 1 Good flexibility, can be bent to some extent Low power (100-500D) Negative power: 0.25-0.40mm Positive power: 0.25-0.40mm 0.3-0.35mm 2 Good flexibility, can be bent to some extent Medium power (500-1000D) Negative power: 0.13-0.30mm Positive power: 0.25-0.45mm 0.35-0.40mm 3 Good flexibility, can be bent to some extent High power (1000-2000D) Negative power: 0.08-0.15mm Positive power: 0.45-0.60mm 0.40-0.45mm 4 Brittle, easy to break when bent Low power (100-500D) Negative power: 0.25-0.40mm Positive power: 0.25-0.40mm 0.4-0.45mm 5 Brittle, easy to break when bent Medium power (500-1000D) Negative power: 0.13-0.30mm Positive power: 0.25-0.45mm 0.45-0.50mm 6 Brittle, easy to break when bent High power (1000-2000D) Negative power: 0.08-0.15mm Positive power: 0.45-0.60mm 0.50-0.60mm

[0026] Second step, design the intermediate arc segment R 凸2 .

[0027] The intermediate arc segment curvature radius R is solved by the following formula 凸3 , in order to control the thickness of the middle part ET is 0.3mm-0.6mm:

[0028] ;

[0029] Wherein, CT is the center thickness of the lens, Sag 凸 is the sag of the concave surface, Sag 凸2 is the sag of the intermediate arc segment;

[0030] Wherein, Sag 凸1 can be obtained by the following formula:

[0031] ;

[0032] R 凸1 is the curvature radius of the convex surface of the lens optical zone; mainly determined by the power of the lens, the power is the objective parameter required in the patient's prescription, which is known, once the power is determined, R 凸1 is determined, the designer does not need to design specially, Sag 凸1 is the vector height of the convex curvature radius R 凸1 of the lens optical zone;

[0033] R 凸3 is the curvature radius of the convex surface of the lens middle zone, which needs to be provided by the designer, because the design of ET is different, the number of R 凸2 is different, Sag 凸2 is the vector height of the convex curvature radius R 凸2 of the lens optical zone.

[0034] Diameter of optical zone of the lens; Diameter of intermediate zone of the lens; K is aspheric factor of the lens, wherein 、 K is a design parameter specified by the designer, if the lens is aspheric, K≠0; if the lens is spherical, K=0;

[0035] R 凸4 is the radius of curvature of the convex edge zone of the lens, because the inner surface of the lens has been completely defined by the designer, R 凸1 is not required to be specially designed, the convex and concave edges of the lens are required to be connected, so the radius of curvature of the convex edge zone of the lens R 凸4 is also determined, and the existing convex surface of the scleral lens is designed as two arcs, one arc of R 凸1 of the optical zone, and the other arc is the radius of curvature of the connecting edge, so the designer cannot change the edge thickness of the existing scleral lens, and the present application first increases the design of inserting an arc R 凸2 to achieve the control of ET.

[0036] The value range of the intermediate zone thickness ET is dynamically adjusted according to the lens material and the optical power:

[0037] Tough material, low optical power (100-500 degrees): ET=0.3mm-0.35mm;

[0038] Brittle material, high degree (1000-2000 degrees): ET=0.5mm-0.6mm;

[0039] Third step, introduce transition arc segment R 凸3 .

[0040] The radius of curvature R 凸3 of the transition arc segment is solved by the following formula to smoothly connect the intermediate arc segment and the edge arc segment:

[0041] ;

[0042] wherein, Diameter of optical zone (8.0-12.0mm), Diameter of intermediate zone (12.5-18.0mm), BFW1 is the width of the upper half of the transition arc, Diameter of edge zone (14.5-20.0mm), Sag 凸3a is the sag of the upper half of the convex transition arc, Sag 凸3b is the sag of the lower half of the convex transition arc, R 凸4 is the radius of curvature of the convex edge zone of the lens.

[0043] Transition arc segment R 凸3The curvature radius of the transition arc ranges from 5.0mm to 12.0mm, ensuring smooth connection of the arc segments and uniform stress distribution.

[0044] Fourth step, optimizing edge connection.

[0045] Ensuring the width of the transition arc Satisfies:

[0046] ;

[0047] And = ×0.75 to eliminate lens edge depression and stress concentration.

[0048] Lens manufacturing adopts numerical control lathe processing, as shown in Figure 4 , the lens blank is rotated by C-axis, the tool is fed by X-axis and Y-axis linkage, and the optical zone, the intermediate arc segment and the edge arc segment are turned by three segments.

[0049] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only preferred examples of the present application, and are not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A design method for edge improvement, characterized in that: The following steps are involved: S1. Define lens parameters: Determine the convex curvature radius R of the optical zone according to the lens power 凸1 , and calculate its vector height Sag 凸1 ; S2. Design the middle arc segment R 凸2 : Solve the curvature radius R of the middle arc segment 凸2 , to control the thickness ET of the mid-periphery; In step S2, the middle arc segment R is designed. 凸2 The specific operations are: The curvature radius R of the middle arc segment is solved by the following formulas: 凸2 , to control the thickness ET of the periphery to 0.3mm-0.6mm: ； Among them, CT is the center thickness of the lens, Sag 凸 is the convex sag, Sag 凹 is the concave sag, Sag 凸2 is the sagittal height of the middle arc segment, is the diameter of the optical zone, is the diameter of the mid-circumference area, K is a constant; Among them, Sag 凸1 It can be obtained by the following formula: ； S3, introduce transition arc R 凸3 : Solve the transition arc curvature radius R 凸3 , to smoothly connect the middle arc segment with the edge arc segment; In step S3, the transition arc segment R is introduced 凸3 The specific operations are: The transition arc curvature radius R is solved by the following formulas: 凸3 , to smoothly connect the middle arc segment with the edge arc segment: ； in, is the diameter of the optical zone, and the diameter of the optical zone is 8.0-12.0 mm, is the diameter of the mid-circumference area, and the diameter of the mid-circumference area is 12.5-18.0 mm, is the edge area diameter, the edge area diameter is 14.5-20.0mm, BFW1 is the width of the upper half of the transition arc, BFW2 is the width of the transition arc, Sag 凸3a Sag is the upper half of the convex transition arc. 凸3b is the lower half of the convex transition arc height, R 凸4 is the radius of curvature of the convex surface of the lens edge area; S4. Optimize edge connection: Ensure that the width of the transition arc meets the requirements to eliminate lens edge depression and stress concentration.

2. The edge improvement design method according to claim 1, characterized in that: The value range of the mid-peripheral thickness ET is dynamically adjusted according to the lens material and light intensity: Tough material, low gloss, the low gloss is 100-500 degrees: ET = 0.3mm-0.35mm; Brittle material, height number, the height number is 1000-2000 degrees: ET=0.5mm-0.6mm.

3. The edge improvement design method according to claim 2, characterized in that: The transition arc R 凸3 The curvature radius ranges from 5.0mm to 12.0mm, ensuring smooth connection of arc segments and uniform stress distribution.

4. The edge improvement design method according to claim 3, characterized in that: The specific operation of optimizing edge connections in step S4 is: Ensure that the transition arc width BFW2 satisfies: ； And BFW1=BFW2x0.75 to eliminate lens edge depression and stress concentration.

5. The edge improvement design method according to claim 1, characterized in that: The lens is manufactured by using a CNC lathe, which rotates the lens blank through the C axis and feeds the turning tool in conjunction with the X axis and Y axis, and turns the optical area, the middle arc segment and the edge arc segment in three sections.

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